I saw the guarantee of no string breakage and had to try them. The guarantee is for three months, so for the price, it's about the average of a set a month for me which is how I justified buying them.
So far, they feel great and I love that part of the guarantee is that they won't rust. I wouldn't know this set from the usual set of D'Addarios that I normally use.
I know that if a string breaks, the process of getting a refund is gonna be a hassle, so I'm not putting that on the table. What I like is their confidence in their strings to offer such a claim, so that I can play a lot more aggressively than normal. That's worth it for me right there. I think I'd buy another set when I finally replace my strings.